/**
 * ***************************************************************************** Copyright (c) 2000,
 * 2008 IBM Corporation and others. All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0 which accompanies this
 * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html
 *
 * <p>Contributors: IBM Corporation - initial API and implementation
 * *****************************************************************************
 */
package org.eclipse.ltk.core.refactoring;

/**
 * A content stamp object represent the content of an <code>IFile</code>. A content stamp object is
 * updated whenever the content of a file changes. In contrast to a time stamp a content stamp is
 * reverted to its previous value if the content of the file is reverted back by performing a
 * corresponding undo change.
 *
 * <p>Clients of the refactoring framework don't need to take care of content stamps. They are
 * managed by the framework itself.
 *
 * <p>In version 3.0 not all files in the workspace are annotated with a content stamp. The
 * refactoring framework only adds content stamp to those files where necessary. As of version 3.1
 * the content stamps are mapped to the resource's modification stamp.
 *
 * <p>Content stamp are to be compared using the <code>equals(Object)</code> method. It is not
 * guaranteed that content stamps are identical for identical files.
 *
 * <p>This class is not intended to be extended by clients.
 *
 * @since 3.0
 * @noextend This class is not intended to be subclassed by clients.
 */
public abstract class ContentStamp {

  /**
   * Checks whether the stamp is the null stamp or not. A null stamp is generated for files which
   * either don't exist or exist in a closed project.
   *
   * @return whether the stamp is the null stamp or not.
   */
  public abstract boolean isNullStamp();
}
